Dial synchronizer for circular knitting machines



May 26, 1970 G. BILL! 3,513,667

DIAL SYNCHRONIZER FOR CIRCULAR KNITTING MACHINES Filed Nov. 15, 1968 5 Sheets-Sheet 1 Fig.1

Giorgio 577/4 fnvenfvr y 1970 G. BILL. 3,513,667

" DIAL SYNCHRONIZER FOR CIRCULAR KNITTING MACHINES Filed Nov. 15, 1968 5 Sheets-Sheet 2 Giorgia fil'll/l [/1 van/ah 'grlwvcz May 26, 1970 G. BILLI 3,513,667

DIAL SYNCHRONIZER FOR CIRCULAR KNITTING MACHINES Filed Nov. 15, 1968 5 Sheets-Sheet Gimp/01577: fm f/vzor WW rmmvsys' May 26, 1970 G. BILL! 5 DIAL SYNCHRONIZER FOR CIRCULAR KNITTING MACHINES Filed Nov. 13, 1968 5 Sheets-Sheet 4 G/brg/o Bl/l/l Z venfor United States Patent Int. c1.n04b 15/02 US. Cl. 6695 4 Claims ABSTRACT OF THE DISCLOSURE A synchronizing device for the dial hooks for a circular knitting machine which prevents pattern-controlled displacement of the dial hook control cams between active and inactive positions to obtain the displacement of the cams in the active position at a predetermined rotary position of the dial with respect to the machine frame. The device consists of a circular synchronizing cam on a dial spindle and rotatable therewith, said cam having radial and axial operative surfaces. A cam follower is provided and resiliently connected to a pattern-controlled member for operation thereby in a transverse direction in respect of said dial spindle. A control surface on the cam includes fiat profiles and step circular profiles, the circular profiles each having a peripheral recess and an axially inclined ramp between flat adjacent profiles at the recess. The cam follower when urged by the patterncontrolled member in a transverse direction 'waits until it is reached by one of the recesses, when it enters the recess and is moved axially by the ramp. Thus a control cam for the dial hooks is displaced into its active position in two steps. The cam inactive position is obtained by the axial displacement of the cam follower obtained by a resilient means through a reverse transverse movement of the pattern-controlled member.

This application is a continuation-in-part of my copending application Ser. No. 391,888 filed Aug. 25, 1964, now abandoned.

SUMMARY OF THE INVENTION The present invention relates to circular knitting machines and, more particularly, to a synchronizing device which prevents pattern-controlled displacement of the dial hook control cams from an inactive position into an active position except at a predetermined rotary position of the dial with respect to the machine frame, the active position being reached in two steps to act on the long butts only and then also on the short butts of the hooks.

A circular synchronizing cam is mounted on the dial spindle for rotation therewith. A cam follower is resiliently connected to a pattern-controlled member for operation thereby in a transverse direction. The synchronizing cam has a control surface including fiat profiles and step circular profiles, the circular profiles each having a peripheral recess and an axially inclined ramp leading between fiat adjacent profiles at the recess. When resiliently urged in a transverse direction by the patterncontrolled member the cam follower waits against one step profile until it is reached by the recess. It then enters the recess and is moved axially by the ramp. Axial movement of the cam follower is thus obtained in two steps; the follower displaces a control cam for the dial hooks from the inactive position-in two steps-into the active position. In the particular embodiment which is herein shown and described, there are two cam followers and two pattern-controlled members each of which is asice sociated with a hook cam which is displaceable axially with respect to the dial spindle, to engage in two steps at first the long butts of the dial hooks and then also the short butts of the hooks in its active position and to clear the butts in its inactive position.

The object of the invention is to make the two step displacement of the dial hook cams perfectly synchronized at determined angular positions of the hook dial to avoid damages and breakages of the hook butts. In known arrangements the insertion of these hook cams into the active position is provided directly controlled by the cam pattern provided on the machines within a drum for the program cams, said drum having its own operation. It is hereby diflicult to obtain a hook cam control perfectly synchronized with the hook dial and often disadvantages occur due to this reason. The device according to the invention avoids these disadvantages by always assuring the cam displacement in the active position for the hook control ins a desired instant in respect of the hook dial angular position. Indeed the control to displace a control cam of the hook butts is determined by the circular cam, which is rotatively integral at a predetermined angular position with the hook dial.

A preferred embodiment of the invention is now described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 shows an elevational diagrammatic sectional view taken on a plane passing through the needle cylinder axis;

FIG. 2 is a view and partial section taken on the line II-II of FIG. 1;

FIG. 3 is a view and partial section taken on the line IIIIII of FIG. 1;

FIG. 4 is a section of the development taken along the broken line IV-IV of FIG. 3;

FIG. 5 is a section taken on the line VV of FIG. 1;

FIG. 6 is a bottom partial section taken on the line VI-VI of FIG. 1 to illustrate the hook control cams in a disengaged condition;

FIGS. 7, 8, 9 show sections similar to those of FIG. 6, illustrating different conditions of the cams and their corresponding functions;

FIG. 10 shows an enlarged and more sectional detail of FIG. 1;

FIG. 11 shows in a reduced scale the circular synchronizing cam in an overall view taken on the line XI-XI of FIG. 10;

FIGS. 12 and 13, 14, and 15, 16 and 17, 18 and 19, 20 and 21, 22 and 23 are sections similar to those of FIG. 10 and views similar to those of FIG. 11, taken on the lines XIIIXIII, XVXV, XVII-XVII, XIX-XIX, XXI-XXI and XXIIIXXIII respectively of FIGS. 12., 14, 16, 18, 20 and 22, to illustrate different conditions of the members shown.

DESCRIPTION OF PREFERRED EMBODIMENT In the drawing, with particular reference to FIGS. 1 to 4, 1 denotes the needle cylinder; in the grooves thereof needles 3 slide. A non-rotating circular structure 5 lies above a rotating plate or so called dial 7 in the radial tracks of which conventional hooks 9 slide for the operations on hosiery machines, in particular the kniting of the double initial welt. The unit of hooks 9 is divided into two groups, along two complementary arcs, the

hooks of one group including relatively short butts 9A, and the hooks of the other group including longer butts 9B. The dial 7 is rotated by a spindle 11 coaxial with the needle cylinder and mounted inside a supporting sleeve 13 borne by the machine stationary structure 14.

According to an arrangement per se known, the spindle 11 is rotated synchronously with the needle cylinder and for this purpose a drive is provided comprising a bevel gear 15 which is rotatively integral with a member 17; this member 17 is coupled in rotation with the spindle 11, which is integral with the dial 7. By this arrangement the number of revolutions of the dial 7 corresponds exactly to that of the needle cylinder 1.

A step circular synchronizing cam generally denoted by 19 is integral with the rotating assembly including members 11, 15 and 7. This circular cam in particular comprises: an outer fiat surface 19A, a step cylindrical surface 19B; 3. second intermediate flat surface (19C; a second intermediate step cylindrical surface 19E; a third fiat surface 19F; and a third cylindrical surface 19G. Moreover the cylindrical surface 19B has a radial recess 19H which reaches the profile of the cylindrical surface 19E; in the rotation direction of cam 19 denoted by the arrow f the recess 19H ends with an inclined plane 19H (see in particular FIGS. 2 and 16). Similarly the cylindrical surface 19E has a radial recess 19M up to a distance from the cylindrical surface 196; in the direction of rotation denoted by arrow 1, the recess 19M ends with an inclined plane 19M Cam 19 is designed to control the hooks exactly synchronously with the position of the groups of hooks 9 on the dial 7.

Two control units for two hook displacement cams can cooperate with the circular cam 19 and with its surfaces abovementioned, one of said cams being designed to cause the hook radial displacement in a centrifugal direction i.e. outwardly and the other the radial centripetal displacement i.e. inwardly. Both control units are now described.

The upper ends 21A and 23A of two rods 21 and 23 cooperate with the abovementioned surfaces of cam 19; these rOds are mounted as hereinafter described to be able to move parallel with the axis of spindle 11, as well as about radially to and from said spindle I l. The ends 21A and 23A of rods 21 and 23 are designed to form axial and radial followers intended to cooperate with the flat and circular surfaces, the recesses and the inclined planes of circular cam 19. Rod 21 is mounted slidably at one end of a bell crank 25 which is linked on a small shaft 27 borne by the stationary structure 14 on which also sleeve 13 is mounted. The bell crank 25 at the end opposite that bearing the rod 21, 21A is controlled by a tie rod 31 through a spring 33 (see FIG. 3). The bell crank 25 is further urged by a counter spring 35 (see FIG. 4) which is designed to rotate the bell crank 25 in such a direction as to move the rod 21, 21A away from spindle 11; the tie rod 31 when withdrawn in the direction of arrow f of FIG. 3 stretches resiliently the spring 33 and through this latter rotates lever 25 in a direction opposite that of spring 35 i.e. approaching thereby the rod 21, 21A to the spindle 11, the spring 33 being stronger than spring 35. The rod 23, 23A is similarly mounted on the end of a bell crank 37 which is mounted movable angularly on a small shaft 39 borne by the stationary structure 14. The bell crank 37 is controlled by a tie rod 41 which when withdrawn in the direction of the arrow f of FIG. 3 moves the lever 37 in such a direction as to move rod 23 away from spindle 11; a counter spring 43 (see FIG. 4) is designed to rotate the small lever 37 in an opposite direction in respect of the tie rod 41, i.e. in such a direction as to approach the rod 23, 23A to spindle 111. The rods 21 and 23 at the lower end opposite the end 21A and 23A have each a flat head 21B respectively 23B for the purposes hereinafter described.

On the circular structure 5 a small axially hollow column 45 is mounted which is intended to guide a cam holder member 47 in its vertical movements. The member 47 is further guided on the structure 5 through a screw pivot 49 (see FIG. 5) mounted parallel with the guide column 45; the cam holder member 47 is thus prevented from rotating about the column 45. The member 47 carries at the lower end a cam extension 47A which is a hook displacement cam designed to act on the butts 9A and 9B of the hooks 9. The cam holder member 47 is provided at the upper end with an adjustable follower head 47B which is designed to rest underneath against the flat head 21B of rod 21. The member 47 is urged to rise by a spring 51 and is on the contrary lowerable with the lowering of rod 21 operated as hereinafter described by the cam 19; the same screw 49 can form with its head a stop designed to limit the raising of the cam holder member 47 by the spring 51.

Similarly to what described for member 47, a second cam holder member 53 is provided which is guided on the structure 5 similarly to member 47, has an extension 53A forming a hook displacement cam corresponding to that 47A but differently shaped; the member 53 also has an upper adjustable head 53B similar to the head 47B. The cam holder member 53 is urged upwardly by a counter spring 55, to rest the head 53B underneath against the flat head 23B, and is guided in an axial direction by a small column 57 similar to that 45, and against rotation by a screw 59 similar to that at 49 (see FIG. 5).

The cam extensions 47A and 53A carried by the cam holder members 47 and 53 project through suitable windows 5A and 58 made in the circular structure 5 under the structure 5 itself. In the lower surface of the structure 5 an outer side 61 and an inner side 63 are made along either of which the butts 9A, 9B of hooks 9 can slide. The outer side 61 has a radial recess outwardly, defined by two profiles 61A, 61B in the region of cams 47A and 53A; the inner side 63 has a radial recess 63A inwardly in correspondence of the window 5A for cam 47A.

When an operative cycle of hooks 9 has to begin, the butts 9A, 9B of them are in the condition shown in FIG. 6 i.e. in a circular arrangement adjacent the inner side 63, the cams 47A and 53A being raised not to interfere with the butts 9A, 9B as shown for cam 47A in FIG. 10. At the beginning of an operative cycle of the hooks, cam 47A is two-step lowered from the position shown in FIG. 10, in order to reach subsequently the condition shown in FIG. 16 and the condition shown in FIG. 20, to act respectively only on long butts 9B and then also on short butts 9A; the lowering of cam 47A from the position in FIG. 10 to the position in FIG. 16 can take place while short butts 9A are passing under it; in the position of FIG. 16 cam 47A can begin to act on long butts 9B; while cam 47A acts on long butts 9B it can be lowered from the position in FIG. 16 to the position in FIG. 20 in order to be able to act then also on short butts 9A. The improvement for the two step introduction of cam 47A is known in the art. Cam 53A can be controlled in the same way for the two step insertion.

The lowering of cam 47A causes the displacement of the hook butts as shown in FIG. 7, said butts being displaced from the side 63 outwardly until they almost graze the recess 61A and being then partially withdrawn by profile 61B along the side 61. During the knitting of a double fabric such as that of the welt, the butts 9A, 9B assume the condition shown in FIG. 8 i.e. the hooks are limitedly projecting and circularly distributed along the side 61. At the end of an operative cycle of the hooks, both cams 47A, 53A are inserted as shown in FIG. 9, and the hook butts are displaced outwardly by cam 47A and then inwardly by the cam 53A, until they bring the hook butts adjacent the inner side 63 i.e. in the condition shown in FIG. 6 and thus ready for a new cycle.

As previously stated, the displacement of the cam holder members 47 and 53 are obtained through the rods 21 and 23 by the circular cam 19 and thus the movements of cams 47A and 53A are always positively synchronized with respect to the two groups of hooks 9 with long butts 9B and short butts 9A, because the circular cam 19 is arranged in an angular position perfectly determined with respect to the dial 7 carrying the hooks 9. Outer controls are designed to arrange the operation :by the circular cam 19 as hereinafter described.

Before the hook operation cycle begins, the spring 35 maintains the bell crank 25 in such a position as to keep the rod 21, 21A radially moved away from spindle 11, i.e. in the position shOWn in FIGS. and 11; spring 51 maintains member 47 raised and thus the rod 21 is resting against the surface 19A at a distance from the surface 19B (FIGS. 1, 2, 10, 11). At the cycle beginning when cam 47A is to be inserted, the tie rod 31 stretches spring 33 in the direction of the arrow f and then the bell crank 25 is displaced in the counterclockwise looking at FIG. 3 i.e. in such a direction as to approach rod 21, 21A to spindle 11, i.e. in the direction of the arrow f of FIG. 12; in this manner the follower 21A rests against the cylindrical surface 19B (see FIG. 13) of the circular cam 19; by rotation of circular cam 19 in the direction of arrows h the recess 19H reaches follower 21A and in this moment the rod 21 can further move to the spindle 11 i.e. in the direction of arrow f of FIGS. 12 and 14, to the bottom of recess 19A (FIGS. 14 and 15). By further rotation of circular cam 19 the follower 21A is reached by the inclined plane 19H and is then axially urged downwardly until it reaches the flat surface 190; by the action of spring 33 the follower 21A then rests radially against the cylindrical surface 19E (see FIGS. 16 and 17). The displacement downwardly of rod 21 causes the partial insertion of the cam 47A to act only on long butts 9B of hooks 9 (see FIG. 16). It is noted that the angular position of the inclined plane 19H is such as to allow the lowering of cam 47A in the right instant i.e. with a desired timing with respect to the position of the hook groups 9 having long butts 9B and short butts 9A. It is further noted that the action of rod 21 on the member 47, 47B is possible in this and in the other positions subsequently reached by rod 21 in the direction of the arrow f owing tothe extension of the lower head 21B. The spring 33 of tie rod 31 continues to keep the rod 21 urged in the direction of the arrow f i.e. in a substantially radial direction in respect of the view in FIGS. ll, 13, 15, 17, 19. Prosecutingthe rotation of the circular cam 19 the recess 19M is brought at the follower 21A and thus the rod 21-21A move further in the direction of the arrow f until it reaches the recess 19M (see FIGS. 18 and 19). By further rotation of the circular cam 19 the inclined plane 19M contacts the follower 21A and this latter is urged further downwardly to the position shown in FIGS. and 21, passing then instantaneously in the position shown in FIGS. 22 and 23, rested against the cylindrical surface 19G, still owing to the action of spring 33. This further lowering of rod 21 causes the full insertion of cam 47A to act also on the short butts 9A; also this insertion is timed with the angular position of the inclined plane 19M When the stage determined by the full insertion of cam 47A is accomplished (said stage being illustrated in FIG. 7), to disengage the cam 47A it is only necessary to stop the pull action of the tie rod 31 and then to loosen the spring 33. Under these conditions the spring 35 acting on the bell crank displaces this latter and then the rod 21 so that the rod 21 moves radially away from spindle 11 and is being displaced from the fiat surface 19F to the surface 19C and to the surface 19A, said rod 21 being urged downwardly by the spring 51. It is noted that contrary to the insertion operations of cam 47A, the disengagement operations of cam 47A do not require any timing i.e. any synchronism with respect to the position of the long butts 9B and short butts 9A of hooks 9.

After disengaging the cam 47A the condition shown in FIG. 8 is established.

When both cams 47A and 53A are to be inserted almost simultaneously to obtain the stage illustrated in FIG. 9 the tie rod 31 is again withdrawn while the tie rod 41 is loosened which hitherto was acting on the small bell crank 37 to maintain the rod 23, 23A radially moved away from spindle 11 i.e. in a position corresponding to that shown in FIG. 10 for the rod 21; the loosening of tie rod 41 causes a radial urging in a centripetal direction of the follower 23A on acting of spring 43, while spring 33 tensioned by tie rod 31 urges the lever 25 in such a direction as to press once again the rod 21, 21A too in the centripetal direction i.e. in the direction of the spindle 11. Both followers 21A, 23A and then both rods 21, 23 accomplish the same movements previously described for the rod 21, 21A only. The controls operated by the rods 21, 23 are almost simultaneous; indeed these rods are in angular close positions with respect to the axis of spindle 11 and of cam 19 so that these rods are affected immediately after each other by the recess 19H, the inclined plane 19H and then by the recess 19M and the inclined plane 19M owing to the angular staggering of both earns 47A and 53A, the action of these cams on a same hook butt occurs during the passage of this butt in correspondence of both cams; in other words the slight time difference of the action of cam 19 on both rods 21 and 23 is balanced by the same angular staggering of both cams 47A and 53A.

After all the hooks have been brought through the path denoted in FIG. 9 against the inner side 63, the tie rod 31 can be loosened and the tie rod 41 can be withdrawn; thus the two rods 21 and 23 are moved away in a radial direction from spindle 11 and both cams 47A and 53A are disengaged after each other; this allows to reach the position of the hooks against the side 63, as illustrated in FIG. 6, by action of the raising obtained through the spring 51 and the spring 55 and by the action of the followers 21A and 23A passing from surface 19F to surface 19C and then to surface 19A.

It should be noted that, as already stated hereinbefore, the disengagement of the two hook displacement cams 47A and 53A from the operative condition shown in FIG. 9 can be accomplished at any moment without prejudice. Only the insertion of one cam respectively of each cam 47A and/or 53A has to occur with a determined timing with respect to the distribution of the dial hook butts; this timing is always assured because the circular cam 19 is rotatively combined with the dial 7.

The device as above described thus comprises: the circular cam 19 rotating synchronously with the dial 7; a first control unit including the members 21, 25, 31, 33, 35, 47, 51 and the hook displacement cam 47A for the centrifugal displacement of books 9; and a further control unit including the members 23, 37, 41, 43, 53, 55 and the hook displacement cam 53A for the centripetal displacement of the hooks 9.

I claim:

1. In a circular stocking machine having a vertical rotating needle cylinder, a stationary structure overlying the needle cylinder, a dial for radial hooks which is coaxial with the needle cylinder and rotating, a dial spindle carried by said stationary structure and operating said dial and extending coaxially above the needle cylinder, radially movable hooks on said dial divided into two groups, the hooks of one group having long control butts and the hooks of the other group having short control butts, on the dial hook displacement cam means movable to act on said long butts and on said short butts with a two step displacement, a synchronizing device of the hook control cams comprising: a circular synchronizing cam for a radial and axial action, angularly integral with said spindle above said stationary structure, said cam including on its lower surface a first outer flat surface, a first cylindrical surface forming a first step downwardly with a first radial recess, a second intermediate flat surface, a first inclined front plane directed downwardly between said recess and said second intermediate flat surface, a second intermediate cylindrical surface forming a second step downwardly with a second radial recess, a third inner flat surface, a front inclined plane directed downwardly between said second recesses and said third flat inner surface and a third inner cylindrical surface;

and said device further comprising: one control unit which comprises on the stationary structure a cam holder member guided on said stationary structure for vertical movements, said cam holder member forming lowerly a hook displacement cam designed to act on the hook butts, and upperly a follower head; a spring urging said cam holder member upwardly in such a direction as to move away said displacement cam from the action on the hook butts; on the stationary structure a bell crank movable about a pivot carried by said structure; on said bell crank a vertical rod slidable vertically and forming an axial and lateral follower at the upper end to cooperate with said circular synchronizing cam and a fiat head at the lower end, said rod being carried horizontally by said bell crank to move radially with respect to said circular synchronizing cam, and said follower head of the cam holder member being pressed by said spring means underneath against said fiat head in all the positions assumed by said rod, to press said rod against said circular synchronizing cam; resilient control means designed to act on said bell crank to urge it in such a direction as to approach said rod transversally to the dial spindle so that, when said resilient control means are active, said rod is pressed lat erally against said first cylindrical surface of the circular synchronizing cam while this latter is rotating and into said first recess, is urged partially downwardly by the first inclined plane, is pressed laterally against said second cylindrical surface of the circular synchronizing cam and into said second recess, is further urged downwardly by the second inclined plane, and is then laterally pressed again against said third cylindrical surface; counter means for disengagement designed to act on said ball crank in an opposite direction with respect to the resilient control means to movewhen they are activesaid rod transversally away from said dial spindle along said circular synchronizing cam up to in front of said first outer flat surface; said rod when urged partially downwardly causing the partial insertion downwardly of said hook dis placement cam during the passage of the short butts to act then on the long butts, and when moved further downwardly causing the total insertion downwardly of said hook displacement cam during the transit of the long butts to act then also on the short butts; when said rod is moved away from said dial spindle said spring of the cam holder member causing the raising of said cam holder member and of said hook displacement cam off work as well as the raising f said rod against said first outer fiat surface.

2. A device according to claim 1, wherein said hook displacement cam is a centrifugal displacement cam of the hooks i.e. outwardly, and further comprising another control unit similar to said one control unit for a further centripetal displacement cam of the hooks, said another control unit cooperating with the same circular synchronizing cam.

3. In a circular stocking machine having a vertical rotating needle cylinder, a stationary structure overlying the needle cylinder, a dial for radial hooks which is coaxial with the needle cylinder and rotating, a dial spindle carried by said stationary structure and operating said dial and extending coaxially above the needle cylinder, radially movable hooks on said dial divided into two groups, the hooks of one group having long control butts and the hooks of the other group having short control butts, on the dial hook displacement cam means movable to act on said long butts and on said short butts with a two step displacement, a synchronizing device of the hook control cams including: a circular synchronizing cam for a radial and axial action, angularly integral with said spindle above said stationary structure, said cam including on its lower surface a first outer fiat surface, a first cylindrical surface forming a first step downwardly with a first radial recess, a second intermediate fiat surface, a first inclined front plane directed downwardly between said recess and said second intermediate fiat surface, a second intermedi ate cylindrical surface forming a second step downwardly with a second radial recess, a third inner fiat surface, a front inclined plane directed downwardly between said second recess and said third fiat inner surface and a third inner cylindrical surface; and said device further comprising one control unit which comprises: on the stationary structure a cam holder member guided on said sta tionary structure for vertical movements; said cam holder member forming lowerly a hook displacement cam de signed to act on the hook butts; a spring urging said cam holder member upwardly in such a direction as to move away said displacement carn from the action on the hook butts; a drive member forming an axial and lateral follower at the upper end to cooperate with said circular synchronizing cam, said drive member being movable horizontally to move radially with respect to said circular synchronizing cam and movable vertically; said cam holder member being pressed by said spring means underneath against said drive member in all the positions assumed by said drive member to press it against said circular synchronizing cam; resilient control means de signed to approach said drive member to the dial spindle so that, when said resilient control means are active, said drive member is pressed laterally against said first cylindrical surface of the circular synchronizing cam while this latter is rotating and into said first recess, is urged partially downwardly by the first inclined plane, is pressed laterally against said second cylindrical surface of the circular synchronizing cam and into said second recess, is further urged downwardly by the second inclined plane, and is then laterally pressed again against said third cylindrical surface; counter means for disengagement designed to act to movewhen they are ac tivesaid drive member transversally away from said dial spindle along said circular synchronizing cam up to in front of said first outer fiat surface; said drive member when urged partially downwardly causing the partial insertion downwardly of said hook displacement cam during the passage of the short butts to act then on the long butts, and when moved further downwardly causing the total insertion downwardly of said hook displacement cam during the transit of the long butts to act then also on the short butts; when said drive member is moved away from said dial spindle, said spring of the cam holder means causing the raising of said cam holder member and of said hook displacement cam off work as well as the raising of said drive member against said first outer flat surface.

4. A device according to claim 3, wherein said hook displacement cam is a centrifugal displacement cam of the hooks i.e. outwardly, and further comprising another control unit similar to said one control unit for a further centripetal displacement cam of the hooks, said another control unit cooperating with the same circular synchroniz' mg cam.

References Cited UNITED STATES PATENTS W. CARTER REYNOLDS, Primary Examiner 

